Multimedia Systems

Lehrstuhl für Informatik 4
Kommunikation und verteilte Systeme
Chapter 2: Basics
Chapter 3: Multimedia Systems – Communication Aspects and Services
Chapter 4: Multimedia Systems
– Storage Aspects
• Optical Storage Media
• Multimedia File Systems
• Multimedia Database
Systems
Chapter 5: Multimedia Usage
Chapter 4.3: Multimedia Database Systems
4.3: Multimedia Database Systems
• Multimedia Database
Management System
• Data Structure
• Operations on Data
• Integration in a Database
Model
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Database Systems
User
Application
Application
User
Database Management System (DBMS)
Database
Data
Data
Data
Data
Data
Data
Chapter 4.3: Multimedia Database Systems
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Multimedia Database Management System
Multimedia System
• Main task of a Database Management System
(DBMS) is to abstract from the details of:
Storage access
Storage management
Application
MDBMS
• Location of the MDBMS:
Embedded between the application
domain and the device domain
Device
System
• Integration into the system:
Through operating system
Communication components
Application
MDBMS
Operating
system
Chapter 4.3: Multimedia Database Systems
Communication
components
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Multimedia Database Management System
• Persistence of data:
Data outlive processing programs and technologies, e.g. companies have to
keep data in databases for several decades
• Consistent view of data:
Synchronization protocols provide a consistent view of data in a multi-user
system
• Security of data:
Transaction concepts ensure security and integrity protection in case of system
failure. Recovery of lost data.
• Query and retrieval of data:
Query languages such as SQL (Structured Query Language) enable formulating
database queries
Each entry has its state information that can be retrieved correctly
Chapter 4.3: Multimedia Database Systems
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Characteristics of MDBMS
• Corresponding storage media
Multimedia data must be stored and managed according to the specific
characteristics of the available storage media
• Descriptive search methods
Query of multimedia data should base on a descriptive and content-oriented
search, e.g. “Picture of a woman with a red scarf”
• Device-independent interface
Hide details of device control, but offer information on specific characteristics of
available storage media (read-only, write-once, write-many)
• Format-independent interface
DBMS must hide internal storage format and offer conversions to formats
requested by the applications (GIF, TIFF, JPEG, ....)
This allows changing to new storage technologies without any impact on
multimedia applications
Chapter 4.3: Multimedia Database Systems
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Characteristics of MDBMS
• View-specific and simultaneous data access
Allows consistent, multiple and simultaneous data access through different
queries of several applications (e.g. shared editing)
• Management of large amounts of data
DBMS must be capable of handling and managing large amounts of data. Need
of appropriate referencing mechanisms.
• Relational consistency of data management
Relations among data of one or different media must stay consistent
corresponding to their specification. MMDBMS manages the following relations:
• Attribute Relation: supports different presentation (audio, video, image) of
one object
• Component Relation: includes all parts belonging to one data object
• Substitution Relation: defines different kinds of presentation of the same
information, e.g. equation as tables, graphs, animation
• Synchronization Relation: describes temporal relations between data units,
e.g. lip synchronization of audio and video
Chapter 4.3: Multimedia Database Systems
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Characteristics of MDBMS
• Real-time data transfer
DBMS must perform read and write operations of continuous data in real-time
The data transfer of continuous data has a higher priority than other database
management actions
Primitives of multimedia operating systems should be used to support the realtime transfer of continuous data
• Long transactions
The transfer of large amounts of data will take a long time and must be done in
a reliable fashion
Chapter 4.3: Multimedia Database Systems
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Characteristics of MDBMS
• Relation between the operating system and MDBMS:
The operating system provides the management interface for MDBMS to all
local devices
The MDBMS provides an abstraction of the stored data and their equivalent
devices, as is the case in DBMS without multimedia
The communication system provides for MDBMS abstractions for
communication with entities at remote computers
Operating system and communication system can unify all the different
abstractions and offer them
Chapter 4.3: Multimedia Database Systems
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Data Structure
Data can be stored in databases as
• Unstructured (unformatted): data are presented in a unit where content cannot be
retrieved by accessing any structural detail
Example: “Mr. Penguin is a student in the seventh term.”
• Structured form (formatted): data are stored in variables, field or attributes with
corresponding values
Example:
o.student.surname = “mustername”
o.student.name
= “hermann”
o.student.age
= 41
Chapter 4.3: Multimedia Database Systems
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Data Types
Multimedia data can be stored in databases as raw, registering and descriptive data
types:
• Raw Data: represent the unformatted information content, e.g. letters, pixel, values
• Registering data: necessary for correct interpretation and identification of the data;
usually concealed in the header. For example: format-description (GIF, TIFF,
JPEG, ASCII, EBCDIC, ...), compressed/uncompressed data, etc.
• Descriptive data: information about content and structure of the multimedia data to
make use easier and faster, e.g. semantic search
Chapter 4.3: Multimedia Database Systems
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Data Types - Examples
Text
• Characters represent raw data
• Registering data describe the coding (e.g., ASCII)
• Descriptive data may include information for layout and logical
structuring of the text, or keywords
Image
• Pixels represent raw data
• Registering data include the height and width of the picture
• Descriptive data are individual lines, surfaces and subjects
Chapter 4.3: Multimedia Database Systems
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Data Types - Examples
Video sequence
• Pixel matrices represent the raw data
• Registering data provides, in addition to other information, the number of images per
second
• Descriptive data provide a scene description, e.g. ”Jan‘s birthday party”
Audio sequence
• The digital sample values created by a simple PCM coding represent the raw data
• Registering data represent the properties of the audio coding
• Descriptive data represent the content of the audio
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Operations on Data
An MDBMS must offer, for all data types, corresponding operations for:
• archival and
• retrieval
The media related operations will be handled as part or extension of query languages,
e.g. SQL
Different classes of operations are needed:
• input
• output
• modification
• deletion
• comparison
• evaluation
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Operations on Data
• Input (insert / record) operation:
Data will be written to the database
The raw and registering data are always needed, descriptive data can be
attached later
• Output (play) operation:
Read the raw data from the database according to the registering data
• Modification:
Changing of raw, registering and descriptive data
Modification can also be understood as a data conversion from one format to
another
• Deletion operation:
Remove an entry from the database
The consistency of the data must be preserved
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Operations on Data
• Comparison:
Many queries to the MDBMS consist of a search and retrieval of the stored data
Queries are based on comparison information
Individual patterns in the particular medium are compared with the stored raw
data → not successful enough
→ Pattern matching, search in descriptive data, etc.
• Evaluation:
Generation of the corresponding descriptive data from the raw and registering
data
Chapter 4.3: Multimedia Database Systems
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Integration in a Database Model
Design of multimedia database systems base on two different kinds of DBMS:
• ERDBMS (Extensible Relational Database Management System):
Definition of additional, application-dependent data types as domains for
attributes
Definition of new functions to control behavior of and access to the data
Embedding new types and functions into existing RDMBS
• OODBMS (Object-Oriented Database Management System):
Different media are represented by classes, whose instance variables include
the data as internal state
Class hierarchy allows object relations, offers well information navigation and
flexible presentation possibilities
Chapter 4.3: Multimedia Database Systems
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Relational Database Model
Simplest possibility to implement a multimedia database is to use the relational
database model
• The attributes of different media in relational databases are defined
• Attributes can specify
text
audio
video
• Advantage
compatibility with existent database applications
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Relational Database Model - Example
A relation “student” is given:
Student (
Admission_Number
Name
Picture
Exercise_Device_1
Exercise_Device_2
)
Integer,
String,
Image,
Video,
Video
• A relation’s attributes can be specified
through different media types: image,
exercise, video
• Other entries are ”athletics”,
”swimming” and ”analysis”
Chapter 4.3: Multimedia Database Systems
Athletics (
Admission_Number
Qualification
The_High_Jump
The_Mile_Run
)
Integer,
Integer,
Video,
Video
Swimming(
Admission_Number
Crawl
)
Integer,
Video
Analysis (
Qualification
Error_Pattern
Comment
)
Integer,
String,
Audio
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Relational Database Model
• Type 1 Relational Model
Value of a certain attribute can be fixed over the particular set of the
corresponding attribute types, e.g. the frame rate of the video can be fixed
In the example, the videos from the exercise devices 1 and 2 will play at the
fixed rate defined by the type 1 specification
• Type 2 Relational Model
A variable number of entries can be defined through the type 2 relational model
In the example, the individual disciplines of each admitted student are identified
through their admission numbers
• Type 3 Relational Model
Additionally, an entry can simultaneously belong to several relations
In the example, a video entry of a student can be assigned to the relation
”athletics” as well as to the relation ”analysis”
Chapter 4.3: Multimedia Database Systems
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Object-oriented Database Model
In object-oriented databases...
• classes with objects are defined
• objects can be put in relations via a class hierarchy
• a semantic specialization of classes and objects can
follow
Example
• Main class: sports institute
• Subclass: athletics, swimming
• Objects: students
Advantage:
• These system offer good information navigation and
flexible presentation possibility
sports institute
athletics
swimming
students
Disadvantage
• Query operations are incompletely supported
Chapter 4.3: Multimedia Database Systems
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Conclusions
Media can be stored in many ways, only a few were talked about::
Optical Storage
• Compact Disc (CD) for multimedia data like images
• Digital Versatile Disc (DVD) for videos as main medium
• Important: new error protection mechanisms like Reed-Solomon code
Hard disk / file systems
• Different requirements to between “normal” data and multimedia data
• Suitable data structuring needed
• New strategies for disk scheduling needed
Databases
• Can base on relational or object-oriented models
• Structure and behavior of data has to be stored
• New language primitives are needed
• Needed here: more work on transaction management and content-based retrieval of data
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